Gradually pushed the usual Old English word, smearcian (modern smirk), into a specific, unpleasant sense. Of the eyes, from 1759. Figuratively, as indicating favor or encouragement, from c.1400. Romance, Celtic, and Slavic languages tend to use a diminutive of the word for "laugh" to mean "smile" (e.g. Latin ridere "laugh;" subridere "smile"), perhaps literally "small laugh" or "low laugh."